Observations

Description

Valves are lanceolate, with rounded ends, 9-12 µm wide, 30-60 µm long. The raphe is filiform, with the central portions of the branches and central raphe endings slightly deflected towards the primary side of the valve. Terminal raphe fissures are hooked towards the secondary side. The axial area is narrow, linear. The central area is rounded rectangular or square. Striae are radiate, but convergent at the valve apices, 10-13 in 10 µm. Areolae ~32 in 10 µm.

Valves lanceolate with rounded ends. Striae radiate through most of the valve, becoming convergent at the ends. Central area is a somewhat rounded rectangle, or it may be square or irregular (asymmetric). The proximal raphe ends are are rather distantly placed from one another.

Compare

The valve ends of N. lanceolata are not apiculate, as they are in N. germainii. The valve is also broader in N. lanceolata and the striae are coarser. Navicula viridula is larger in size, with lower striae and areolae densities.

North American Diatom Ecological Database (NADED)

Autecology Discussion

Habits

Size Range

Motility

moderately motile (e.g. Navicula tripunctata)

Attachment

unattached

Habitat

benthic

Colony

EMAP Assessment

The Environmental Protection Agency (EPA) western Environmental Monitoring and Assessment Program (EMAP) study was completed during the years 2000-2004 (see citations at bottom of this page). Over 1200 streams and rivers in 12 western states (Arizona, California, Colorado, Idaho, Montana, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington and Wyoming) were selected for sampling based on a stratified randomized design. This type of design insures that ecological resources are sampled in proportion to their actual geographical presence. Stratified randomized design also allows for estimates of stream length with a known confidence in several “condition classes” (good or least-disturbed, intermediately-disturbed, and poor or most-disturbed) for biotic condition, chemistry and habitat.

EMAP Distribution

Navicula lanceolata

Distribution

The distribution map represents the relative abundance of this Navicula lanceolata in the western EMAP study. Relative abundance is a measure of the proportion of cells of this species based on a "fixed count" of 300 total diatom cells counted and identified. Each of the western EMAP sample sites is shown, either with a black dot for sites where Navicula lanceolata was not recorded, or with a red circle indicating the relative abundance of Navicula lanceolata.

Note that the size of the proportional symbols varies between species to help show both abundant and rare species.

Scale for the map to the left

EMAP Response Plots

Navicula lanceolata

Responses

The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Navicula lanceolata from all the stream reaches where it was present. Note that the relative abundance scale is the same on each plot. Explanation of each environmental variable and units are as follows:

ELEVATION = stream reach elevation (meters)STRAHLER = distribution plot of the Strahler Stream Order SLOPE = stream reach gradient (degrees)W1_HALL = an index that is a measure of streamside (riparian) human activity that ranges from 0 - 10, with a value of 0 indicating of minimal disturbance to a value of 10 indicating severe disturbance.PHSTVL = pH measured in a sealed syringe sample (pH units)log_COND = log concentration of specific conductivity (µS/cm)log_PTL = log concentration of total phosphorus (µg/L)log_NO3 = log concentration of nitrate (µeq/L)log_DOC = log concentration of dissolved organic carbon (mg/L)log_SIO2 = log concentration of silicon (mg/L)log_NA = log concentration of sodium (µeq/L)log_HCO3 = log concentration of the bicarbonate ion (µeq/L)EMBED = percent of the stream substrate that is embedded by sand and fine sedimentlog_TURBIDITY = log of turbidity, a measure of cloudiness of water, in nephelometric turbidity units (NTU).DISTOT = an index of total human disturbance in the watershed that ranges from 1 - 100, with a value of 0 indicating of minimal disturbance to a value of 100 indicating severe disturbance.